Nonassociative differential geometry and gravity with non-geometric fluxes

We systematically develop the metric aspects of nonassociative differential geometry tailored to the parabolic phase space model of constant locally non-geometric closed string vacua, and use it to construct preliminary steps towards a nonassociative theory of gravity on spacetime. We obtain explicit expressions for the torsion, curvature, Ricci tensor and Levi-Civita connection in nonassociative Riemannian geometry on phase space, and write down Einstein field equations. We apply this formalism to construct R-flux corrections to the Ricci tensor on spacetime, and comment on the potential implications of these structures in non-geometric string theory and double field theory.Comment: 50 pages; v2: corrected comparison of curvature to ref. [14]; v3: clarifying comments added; Final version to be published in JHE

Bone marrow dendritic cells deficient for CD40 and IL-23p19 are tolerogenic in vitro

Objective(s): In addition to pro-inflammatory role, dendritic cells (DCs) can also be anti-inflammatory when they acquire tolerogenic phenotype. In this study we tested the role of CD40 and IL-23p19 in antigen presenting function of bone marrow-derived DCs (BMDCs) by comparing BMDCs derived from CD40 knockout (CD40KO-DCs) and IL-23p19 (IL-23p19KO-DCs) knockout mice with those from C57BL/6 mice (Cont-DCs). We have focused on CD40 and IL-23, as these molecules have well established pro-inflammatory roles in a number of autoimmune and inflammatory diseases. Materials and Methods: The expression of maturation markers MHC II and co-stimulatory molecules CD40, CD80, and CD86 was analyzed by flow cytometry, while the expression of CD40 and IL-23p19 was measured by RT-PCR. The capacity of BMDCs to activate CD4+ T cells was evaluated by 3H-thymidine incorporation, and the capacity of BMDCs to uptake antigen was evaluated using fluorescent OVA and flow cytometry. Results: The lack of CD40 or IL-23p19 had no effect on uptake of FITC-OVA by the DCs, confirming their immature phenotype. Moreover, CD40KO-DCs had significantly reduced capacity to stimulate proliferation of CD4+ T cells. CD4+ T cells activated by CD40KO-DCs and IL-23p19KO-DCs produced significantly less IFN-γ (P-value ≤0.05), while CD4+ T cells stimulated by IL-23p19KO-DCs produced less GM-CSF and more IL-10 than Cont-DCs. Conclusion: This study shows that CD40KO-DCs and IL-23p19KO-DCs have a marked tolerogenic potency in vitro. Future in vivo studies should determine if and to what extent DCs lacking CD40 or IL-23 have a potential to be useful in therapy of autoimmune inflammation

Family-Friendly Work Environment? An Investigation of Women\u27s Job Stress and Satisfaction

Little research has focused on women with and without children in the workplace and their work-life balance. This study is conducted through the lens of organizational culture in order to determine how different workplace policies can influence women and their job satisfaction and level of job stress. The participants for this study included 172 female students and staff (working full and part time) from an institution of higher education in South Texas. Results showed no significant differences in women\u27s job satisfaction or stress level at work, regardless of having children or not. However, there is a positive relationship between women\u27s job satisfaction and perceived family-friendly culture as well as a negative relationship between women\u27s job stress and perceived family-friendly culture. Organizations must implement family-friendly policies because it is clear when women feel that they have achieved a work-life balance, they are more satisfied at work and therefore are better employees

Microbes in the built environment

The COVID-19 pandemic has encouraged scientists and the general population to think more than ever before about how we interact with microbes in our indoor spaces. Research investigating transmission of SARS-CoV-2 has advanced our knowledge significantly in the last two years. However, indoor and built environment microbiomes are extremely complex polymicrobial systems. We have barely scratched the surface in our understanding of the microbial inhabitants of our indoor and urban spaces. The Microbes in the Built Environment Collection showcases recent research in this important topic around the globe

New Matrix Series Formulae for Matrix Exponentials and for the Solution of Linear Systems of Algebraic Equations

The solution of certain differential equations is expressed using a special type of matrix series and is directly related to the solution of general systems of algebraic equations. Efficient formulae for matrix exponentials are derived in terms of rapidly convergent series of the same type. They are essential for two new solution methods, especially beneficial for large linear systems, namely an iterative method and a method based on an exact matrix product formula. The computational complexity of these two methods is analysed, and for both of them, the number of matrix exponential-vector multiplications required for an imposed accuracy can be predetermined in terms of the system condition. The total number of arithmetic operations involved is roughly proportional to n2, where n is the matrix dimension. The common feature of all the series in the results presented is that starting with a first term that is already well-conditioned, each subsequent term is computed by multiplication with an even better conditioned matrix, tending quickly to the identity matrix. This contributes substantially to the stability of the numerical computation. A very efficient method based on the numerical integration of a special kind of differential equations, applicable to even ill-conditioned systems, is also presented